Demon/Incubus/vampire:I'll admit it. Young woman running into sinister creature of the dark, being taken away or forced on the spot is pretty hot, in my catagory. I'll leave it at that.

I'm imagining a younger woman or older h.s. student experimenting with witchcraft and inadvertently calling forth an incubus. The incubus possesses her boyfriend who, looking on with much skepticism, now possessed proceeds to ravage the girl...much to her delight. Not a deep plot, but could be fun.